It would be better to develop the c8-bishop first.
5. f1e2 Other moves are also tempting. 5... h5g7 Theoretically this was the bishop's square, but perhaps Black's position is a little better than it seems, since the knight can go to f5 or e6, with some luck. 6. h2h4 I'm not sure this move helps White's position. 6... h7h5  7. c1g5 